1. Field of the Invention
The present invention relates to a localization system (hereinafter may be referred to as a position measurement system) and a localization method (hereinafter may be referred to as a position measurement method) enabling localization even in a space in which signals from a GPS (Global Positioning System) satellite cannot be received.
2. Description of the Related Art
Conventionally, GPS has been used as a technology for localization in an outdoor setting. For example, GPS has been used in car navigation systems. In addition, in recent years, cellular telephones and notebook computers have been equipped with a GPS terminal, as the size of the GPS terminal has been made smaller.
According to the GPS system, a plurality of GPS satellites (space satellites) transmit a microwave signal holding time data. The GPS terminal receives this microwave signal. Based on this microwave signal, the GPS terminal obtains the present location of the own device. Therefore, at a place in which microwaves transmitted from the GPS satellites cannot be received, the GPS terminal cannot measure the present position of the own device.
In response to these types of problems, a system is suggested, in which a microwave signal transmitted from a GPS satellite is artificially created at a transmitter station on the ground (for example, in a room interior) as a light signal. Thus, according to this suggested system, positions can be measured even in a place in which microwaves transmitted from the GPS satellite cannot be received (refer to Japanese Unexamined Patent Application No. 2005-77172 (“Patent Document 1”)).
However, according to the technology disclosed in Patent Document 1, it is difficult to improve the accuracy of the measurement, when the measurement precision was inadequate. Considering such problems, an object of the present invention is to provide a localization system and a localization method that enables a measurement of a position in a space in which signals from the GPS satellite cannot be received, and further improves the accuracy of the measurement.